1. Field of the Invention
This invention relates to an operation device of a transmission comprising the combination of a manual multi-range transfer and an automatic transmission.
2. Description of the Prior Art
In four-wheel drive vehicles, there is known conventionally a driving system which comprises the combination of an automatic transmission and a manual multi-range transfer. In the driving systems, a driving system having a structure wherein the manual multi-range transfer has structurally a neutral state is also known. Some manual multi-range transfer devices are equipped with a two-range switching device for switching to either a high speed range and a low speed range. In the manual multi-range transfers in general in part-time four-wheel drive vehicles, a switching operation of the driving system to the high speed range and the low speed range and a switching operation of the driving system to two-wheel drive and four-wheel drive are effected by one transfer lever. Moreover, the switching operation between two-wheel drive and four-wheel drive can be effected only at the time of the high speed range. An example of an operation device of such a transmission is an interlock mechanism of a transmission disclosed in Japanese Utility Model Publication No. 23701/1981.
The manual multi-range transfer of the driving system of the part-time four-wheel drive vehicles will be described with reference to FIG. 1. In this manual multi-range transfer, an output shaft 2 is a driving system which transmits driving force to rear wheels while an output shaft 15 is a driving system which transmits the driving force to front wheels. This manual multi-range transfer comprises an input shaft 1 to which the driving force of an engine is transmitted through a clutch or the like, an output shaft 2 for the rear wheels which is disposed on the axis of the input shaft 1, a synchronizing device 5 as a connecting device which is interposed between the input shaft 1 and the output shaft 2, and a counter shaft 3 which is disposed in parallel with the input shaft 1 and the output shaft 2. The counter shaft 3 is equipped with a gear 7 as a first gear which always meshes with an input gear 6 fitted rotatably to the input shaft 1 and a gear 9 as a second gear which always meshes with a gear 8 fixedly disposed on the output shaft 2. Furthermore, the input shaft 1 is fixed integrally to a clutch hub 16 constituting the synchronizing device 5. If the transfer is constructed as described above, it can be switched to the high speed range where the input shaft 1 is directly coupled to the output shaft 2 or to the low speed range where it is coupled to the latter through the counter shaft 3. In other words, when a driver operates a transfer lever (not shown, refer to reference numeral 28 in FIG. 4) and moves the sleeve 4 of the synchronizing devices to the right in the drawing, the sleeve 4 meshes with a dog gear 11 which is spline-fitted to the gear 8 through a synchronizing ring (not shown, refer to reference numeral 31 in FIG. 5). Accordingly, the power transmission system becomes the input shaft 1.fwdarw.the clutch hub 16.fwdarw.the sleeve 4.fwdarw.the dog gear 11.fwdarw.the gear 8.fwdarw.the output shaft 2, and the high speed range where the input shaft 1 is coupled directly to the output shaft 2 can be obtained. When the driver operates the transfer lever and moves the sleeve 4 in the synchronizing device 5 to the left in the drawing, the sleeve 4 meshes with a dog gear 10 spline-fitted to the input gear 6 through the synchronizing ring (not shown, refer to reference numeral 48 in FIG. 5). Accordingly, the power transmission system becomes the input shaft 1.fwdarw.the clutch hub 16.fwdarw.the sleeve 4.fwdarw.the dog gear 10 .fwdarw.the input gear 6.fwdarw.the gear 7.fwdarw.the counter shaft 3.fwdarw.the gear 9.fwdarw.the gear 8.fwdarw.the output shaft 2, and the low speed range where the input shaft 1 is coupled to the output shaft 2 through the counter shaft 3 can be obtained.
This manual multi-range transfer provides a driving system for four-wheel drive vehicles of a part-time four-wheel drive type wherein the driving force is transmitted to the front wheels and to the rear wheels, or a driving system for two-wheel drive vehicles wherein the driving force is transmitted only to the rear wheels. First of all, as to the driving system of the front wheels, a gear 12 meshing with the gear 9 is rotatably fitted to the output shaft 15. A clutch hub 17 is fixedly fitted to the output shaft 15. In this transfer the driver slides and moves the sleeve 14 meshing always with the clutch hub 17 to the right in the axial direction in the drawing by use of the transfer lever. When the driving system is set to the driving system of the two-wheel drive vehicles, the driver slides the sleeve 4 to the high speed range side by the transfer lever in accordance with the shift pattern shown in FIG. 1(A) and after attaining the high speed range of the four-wheel drive vehicles, he slides the sleeve 14 meshing always with the clutch hub 17 to the left in the axial direction in the drawing by the transfer lever. In other words, one transfer lever moves along the orbit of arrow CR in FIG. 1(A). The driving system of the two-wheel drive vehicles can be shifted from the high speed range of the four-wheel drive vehicles by this transfer lever but cannot from the low speed range of the four-wheel drive vehicles. Therefore, the driving system is always coupled to the high speed range when the switching operation is made between four-wheel drive and two-wheel drive. However, a neutral state occurs in the driving system at the time of shift between the high speed range and the low speed range of four-wheel drive.
To obtain the driving system of the four-wheel drive vehicles, therefore, the driver slides and moves the sleeve 14 to the right in the axial direction by the transfer lever so that the sleeve 14 meshes with the dog gear 13 disposed on the gear 12. When the sleeve 12 meshes with the dog gear 13, and the output shaft 15 rotates integrally with the gear 12. Accordingly, the driving force from the input shaft 1 is transmitted to the gear 8 through the driving system of the high speed range and then to the front wheels through the gear 8.fwdarw.the gear 9.fwdarw.the gear 12.fwdarw.the dog gear 13.fwdarw.the sleeve 14.fwdarw.the clutch hub 17.fwdarw.the output shaft 15.
Japanese Utility Model Laid-Open No. 189860/1986 discloses an alarm device of a part-time four-wheel drive vehicle. The alarm device disclosed in this reference includes a four-wheel drive switch for detecting four-wheel drive, a car speed switch for detecting a low speed and a winker switch for detecting the operation of winkers and when three conditions by the operation of these three switches are established, an alarm is raised. The alarm device of a part-time four-wheel vehicle cannot prevent self-run of the vehicle when it is stopped or parked on a slope, or the like.
Japanese Utility Model Laid-Open No. 196827/1986 discloses a shift device of a four-wheel drive transfer. This shift device is a shift device of a four-wheel drive transfer which sequentially shifts two-wheel drive, four-wheel high speed, four-wheel neutral and four-wheel low speed in accordance with the shift operation of the transfer lever and which includes a stopper pin for anchoring a fork rod for selecting high speed, neutral and low speed in the four-wheel drive state in front and at the back of the neutral position, an actuator for coming in and out the stopper pin, and a stopper release switch disposed on the transfer lever and retracting the stopper pin by the operation of the actuator due to the release operation to release the engagement of the fork rod. This shift device discloses the lock mechanism for all the operation mechanisms of the transfer but does not disclose the technical concept that self-run of the vehicle at the stop on the slope or the like is prevented by locking the shift rod in response to the position relation with the control lever of the automatic transmission, that is, the position detection of the control lever.
As the function peculiar to the automatic transmission, however, the mechanical lock mechanism of the driving system in the parking range can be mentioned as a problem. In the actual operation by the driver, the brake is not used conjointly at the stop or parking of the vehicle but the vehicle is mostly stopped or parked by the function of the parking range alone. However, the stop or parking of the vehicle in this parking range can be established only when the driving systems are fully connected. In the operation device of a transmission comprising the combination of the automatic transmission described above with the manual multi-range transfer in the four-wheel drive vehicle, even if the control lever of the automatic transmission is in the lock state in the parking range, for example, the driving system after the sleeve 4 or the input shaft 1 or in other words, the driving systems after the dog gears 10, 11 et seq are not connected to the driving system of the engine and are not restricted if the manual multi-range transfer is in the neutral state, that is, unless the sleever 4 is engaged with the dog gear 10 or 11. Accordingly, the vehicle cannot be kept stopped on the slope or the like. Even when the manual multi-range transfer is at any suitable connecting position, that is, when the sleeve 4 meshes with the dog gear 11 to select the high speed range or when the sleeve 4 meshes with the dog gear 11 to select the low speed range and the vehicle is at halt, there is the risk that the vehicle runs by itself when it is at halt on the slope or the like, if the synchronizing device is moved to the neutral position as the manual multi-range transfer is accidentally operated by mischief of a child, or the like. In this case, the transfer lever of the operation device of the transmission is only one and the switching operation of the driving system between four-wheel drive and two-wheel drive cannot be made unless the transmission is set to the high speed range of four-wheel drive. Accordingly, the driving systems are fully connected between four-wheel drive and two-wheel drive and the neutral position does not exist in the driving systems.
Accordingly, there remains the problem how the operation device of the transmission should be constructed in order to obtain the construction wherein the transfer lever cannot operate when the automatic transmission is selected and set to the parking range and the vehicle is in the stop or parking state and the driving system is kept in the high speed range or low speed range without causing the shift of the manual multi-range transfer to the neutral position.